Hibernate逍遥游记-第10章 映射继承关系-002继承关系树中的根类对应一个表(discriminator、subclass)

1.

2.

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping
 PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <hibernate-mapping >

    <class name="mypack.Monkey" table="MONKEYS">
       <id name="id" type="long" column="ID">
         <generator class="increment"/>
       </id>
       <discriminator column="MONKEY_TYPE" type="string"  />
       <property name="name" type="string" column="NAME" />

       <many-to-one
         name="team"
         column="TEAM_ID"
         class="mypack.Team"
       />

       <subclass name="mypack.JMonkey" discriminator-value="JM" >
          <property name="color" column="COLOR" type="string" />
       </subclass>

       <subclass name="mypack.CMonkey" discriminator-value="CM" >
          <property name="length" column="LENGTH" type="double" />
       </subclass>

     </class>

 </hibernate-mapping>

3.

 <?xml version="1.0"?>
 <!DOCTYPE hibernate-mapping
 PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
 "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 <hibernate-mapping >

   <class name="mypack.Team" table="TEAMS" >
     <id name="id" type="long" column="ID">
       <generator class="increment"/>
     </id>

     <property name="name" type="string"  column="NAME" />
     <set
         name="monkeys"
         inverse="true"
      >
         <key column="TEAM_ID" />
         <one-to-many class="mypack.Monkey" />
      </set>   

   </class>
 </hibernate-mapping>

4.

 package mypack;

 abstract public class Monkey{

     private Long id;
     private String name;
     private Team team;

     /** full constructor */
     public Monkey(String name,Team team) {
         this.name = name;
         this.team = team;
     }

     /** default constructor */
     public Monkey() {
     }

     public Long getId() {
         return this.id;
     }

     public void setId(Long id) {
         this.id = id;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public Team getTeam() {
         return this.team;
     }

     public void setTeam(Team team) {
         this.team = team;
     }
 }

5.

 package mypack;

 public class CMonkey extends Monkey {

     private double length;

     /** full constructor */
     public CMonkey(String name, double length,Team team) {
         super(name,team);
         this.length=length;

     }

     /** default constructor */
     public CMonkey() {
     }

    public double getLength() {
         return this.length;
     }

     public void setLength(double length) {
         this.length = length;
     }
 }

6.

 package mypack;

 public class JMonkey extends Monkey{

     private String color;

     /** full constructor */
     public JMonkey(String name, String color,Team team) {
         super(name,team);
         this.color=color;
     }

     /** default constructor */
     public JMonkey() {
     }

     public String getColor() {
         return this.color;
     }

     public void setColor(String color) {
         this.color = color;
     }

 }

7.

 package mypack;

 import java.util.Set;
 import java.util.HashSet;

 public class Team {

     private Long id;
     private String name;
     private Set monkeys=new HashSet();

     /** full constructor */
     public Team(String name, Set monkeys) {
         this.name = name;
         this.monkeys = monkeys;
     }

     /** default constructor */
     public Team() {
     }

     /** minimal constructor */
     public Team(Set monkeys) {
         this.monkeys = monkeys;
     }

     public Long getId() {
         return this.id;
     }

     public void setId(Long id) {
         this.id = id;
     }

     public String getName() {
         return this.name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public Set getMonkeys() {
         return this.monkeys;
     }

     public void setMonkeys(Set monkeys) {
         this.monkeys = monkeys;
     }
 }

8.

 package mypack;

 import org.hibernate.*;
 import org.hibernate.cfg.Configuration;
 import java.util.*;
 import java.sql.*;

 public class BusinessService{
   public static SessionFactory sessionFactory;
   static{
      try{
        Configuration config = new Configuration().configure();
        sessionFactory = config.buildSessionFactory();
      }catch(RuntimeException e){e.printStackTrace();throw e;}

   }

   public void saveMonkey(Monkey monkey) {
       Session session = sessionFactory.openSession();
       Transaction tx = null;
       List results=new ArrayList();
       try {
        tx = session.beginTransaction();
        session.save(monkey);
        tx.commit();
     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public List findAllJMonkeys(){
       Session session = sessionFactory.openSession();
       Transaction tx = null;

       try {

        tx = session.beginTransaction();
        List results=session.createQuery("from JMonkey").list();
        tx.commit();
        return results;
     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public List findAllMonkeys(){
       Session session = sessionFactory.openSession();
       Transaction tx = null;

       try {
        tx = session.beginTransaction();
        List results=session.createQuery("from Monkey").list();
        tx.commit();
        return results;
      }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

   public Team loadTeam(long id){
       Session session = sessionFactory.openSession();
       Transaction tx = null;
       try {
        tx = session.beginTransaction();
        Team team=(Team)session.get(Team.class,new Long(id));
        Hibernate.initialize(team.getMonkeys());
       tx.commit();
       return team;
     }catch (RuntimeException e) {
       if (tx != null) {
         tx.rollback();
       }
       throw e;
     } finally {
       session.close();
     }
   }

    public void test(){
       List jMonkeys=findAllJMonkeys();
       printAllMonkeys(jMonkeys.iterator());

       List monkeys=findAllMonkeys();
       printAllMonkeys(monkeys.iterator());

       Team team=loadTeam(1);
       printAllMonkeys(team.getMonkeys().iterator());

       Monkey monkey=new JMonkey("Mary","yellow",team);
       saveMonkey(monkey);

   }

   private void printAllMonkeys(Iterator it){
      while(it.hasNext()){
         Monkey m=(Monkey)it.next();
         if(m instanceof JMonkey)
           System.out.println(((JMonkey)m).getColor());
         else
           System.out.println(((CMonkey)m).getLength());
       }
   }
   public static void main(String args[]) {
     new BusinessService().test();
     sessionFactory.close();
   }
 }

9.

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE hibernate-configuration
  PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
  "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

 <hibernate-configuration>
     <session-factory>
         <property name="dialect">
             org.hibernate.dialect.MySQLDialect
         </property>
         <property name="connection.driver_class">
             com.mysql.jdbc.Driver
         </property>
         <property name="connection.url">
             jdbc:mysql://localhost:3306/sampledb
         </property>
         <property name="connection.username">
             root
         </property>
         <property name="connection.password">
             1234
         </property>

         <property name="show_sql">true</property>

         <mapping resource="mypack/Team.hbm.xml" />
         <mapping resource="mypack/Monkey.hbm.xml" />
     </session-factory>
 </hibernate-configuration>

10.

 drop database if exists SAMPLEDB;
 create database SAMPLEDB;
 use SAMPLEDB;

 create table TEAMS (
    ID bigint not null,
    NAME varchar(15),
    primary key (ID)
 );
 create table MONKEYS (
    ID bigint not null,
    NAME varchar(15),
    MONKEY_TYPE varchar(2),
    COLOR varchar(15),
    LENGTH double precision,
    TEAM_ID bigint,
    primary key (ID)
 );

 alter table MONKEYS add index IDX_TEAM(TEAM_ID), add constraint FK_TEAM foreign key (TEAM_ID) references TEAMS (ID);

 insert into TEAMS(ID,NAME) values(1,'ABC Company');

 insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(1,'JM','Tom','yellow',null,1);

 insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(2,'JM','Mike','orange',null,1);

 insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(3,'CM','Jack',null,1.2,1);

 insert into MONKEYS(ID,MONKEY_TYPE,NAME,COLOR,LENGTH,TEAM_ID) values(4,'CM','Linda',null,2.0,1);